Is science infinite? Can it keep giving us profound insights into the world forever? Or is it already bumping into limits, as I argued in The End of Science? In his 2011 book The Beginning of Infinity physicist David Deutsch made the case for boundlessness. When I asked him about consciousness in a recent Q&A he replied: “I think nothing worth understanding will always remain a mystery. And consciousness (qualia, creativity, free will etc.) seems eminently worth understanding.”

Rees, speaking via Skype from Cambridge, reiterated points he made last month in “Is There a Limit to Scientific Understanding?” In that essay Rees calls Beginning of Infinity “provocative and excellent” but disputes Deutsch’s central claim that science is boundless. Science “will hit the buffers at some point,” Rees warns. He continues:

There are two reasons why this might happen. The optimistic one is that we clean up and codify certain areas (such as atomic physics) to the point that there’s no more to say. A second, more worrying possibility is that we’ll reach the limits of what our brains can grasp. There might be concepts, crucial to a full understanding of physical reality, that we aren’t aware of, any more than a monkey comprehends Darwinism or meteorology… Efforts to understand very complex systems, such as our own brains, might well be the first to hit such limits. Perhaps complex aggregates of atoms, whether brains or electronic machines, can never know all there is to know about themselves.

Rees’s view resembles mine. In The End of Science I asserted that scientists are running into cognitive and physical limits and will never solve the deepest mysteries of nature, notably why there is something rather than nothing. I predicted that if we create super-intelligent machines, they too will be baffled by the enigma of their own existence.

In Switzerland I suggested that the riddle of consciousness is a synecdoche for the riddle of humanity. What are we, really? For most of our history, religion has given us the answer. We are immortal souls, children of a loving god, striving to reach heaven or nirvana. Most modern scientists reject these religious explanations, but they cannot agree on an alternative. They have proposed a bewildering variety of answers to the question of what we really are. We are clusters of neurons awash in chemicals, genes shaped by natural selection, egos keeping a lid on ids, software programs, nodes of information in a cosmic web, quantum wave functions.

Several speakers in Switzerland--psychologist Donald Hoffman, philosopher Bernard Kastrup and Buddhist scholar Alan Wallace--challenged whether materialism is the proper framework for understanding minds. They proposed that mind might be more primary than matter.

Science will never resolve these disagreements and converge on a single, true theory of what we are, for two reasons. One is that we will never have a “consciousness meter,” an objective means of measuring consciousness in non-human things. The other is that we are too protean, too creative, to be captured by single theory. Science itself keeps transforming us, with technologies as diverse as brain implants, genetic therapy and LSD and ideas as diverse as queer theory and integrated information theory. To be human means to be a work in progress.

Deutsch’s claim that science is infinite also has a contradiction at its core. He wants science to solve the deepest mysteries, like consciousness, and yet to have more mysteries to solve, forever. That is a radical assertion about the structure of nature, which to my mind reflects wishful thinking rather than hardheaded realism.

Deutsch is both wrong and right. He is wrong that science can solve every mystery, and especially consciousness. We will never understand, once and for all, who we are. But Deutsch is right that science is potentially infinite, if infinite means never-ending. It is precisely because we can never achieve total self-knowledge that we will keep seeking it forever.

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